The effect of TiO2 nanoparticle codeposition on microstructure and corrosion resistance of electroless Ni?P coating

Ni?P?TiO2 nanocomposite coatings with various contents of TiO2 nanoparticles were synthesized by adding TiO2 nanoparticles to Ni?P electroless plating solution. The effects of pH and anionic surfactant sodium dodecyl sulfate (SDS) on the chemical composition of Ni, P, and TiO2 in the coatings were investigated. Scanning electron microscope (SEM), energy dispersive spectrometer (EDX), and X-ray diffractometer (XRD) were used to characterize the morphology, composition, and crystal structure of deposited coatings, respectively. The hardness of nanocomposite coatings was improved greatly compared to Ni?P coating especially after heat treatment. After heat treatment at 400?degrees C for 1?h, an increase in microhardness was observed for heat-treated Ni?P coatings. The hardness was increased from 805 to 1050?Hv for Ni?P?TiO2 coating deposited at 9?g/LTiO2 concentration in the bath. The corrosion resistance of Ni?P?TiO2 coating was significantly increased compared to Ni?P coatings by incorporation of TiO2 nanoparticle.